1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a system and method of routing local number portability (LNP) data in a telecommunications network.
2. Description of Related Art
The term Local Number Portability (LNP) is utilized in connection with several types of subscriber service changes in which a subscriber may keep his original telephone number. For example, LNP may refer to location portability which involves the capability to physically move (port) a subscriber's line connection from one switch to another within a rate center while retaining the subscriber's original telephone number. LNP may also refer to service provider portability which involves changing a subscriber's service from one service provider to another while retaining the subscribers original telephone number. Or LNP may refer to service type portability which involves changing the type of service (for example from POTS to ISDN) while retaining the subscriber's original telephone number. The present invention relates to location portability within a rate center and service provider portability.
FIG. 1 is a simplified block diagram of an existing LNP network configuration. All information about all ported numbers is loaded from a central database system in which several Number Portability Administration Centers (NPACs) 11 are distributed throughout the country. In each area, the LNP data is downloaded from the NPAC 11 to a Local Service Management System (LSMS) 12 in order to populate network elements 13-15 deployed in the LNP network with the ported subscriber data. Each service provider may implement its own LSMS, and each LSMS is notified by the NPAC which numbers are ported. In this way, callers in different networks continue to dial the subscriber's original number, and each network is aware of the fact that the dialed number has been ported, and routes the call accordingly.
The LSMSs communicate with the NPAC over a Common Management Interface Service Element (CMISE) interface 16, over which ported numbers are downloaded to the LSMSs one at a time. The network elements 13-15 may comprise service control points (SCPs) and/or service transfer points (STPs). In the standard configuration, each SCP and STP node is typically populated with the entire national LNP database of ported numbers. To ensure high availability in the network, the nodes are typically deployed as mated pairs with a primary and a backup element for each node. Then, in the switching network, the Service Switching Points (SSPs) may be programmed to interrogate specified SCPs when they need to access the LNP database.
Each ported number is identified by its Numbering Plan Area Office Code (NPA-NXX) where the NPA relates to the area code, and the NXX relates to the exchange code. For example, in the telephone number 214-997-1234, the NPA is 214 and the NXX is 997.
The ported subscriber data downloaded from the NPAC 11 and LSMS 12 for a single subscriber is grouped into a single record called an LNP subscription. The information contained within the LNP subscription is the routing data necessary to route a call to the subscriber's new location or new service provider's switch. The information is categorized as Location Routing Number (LRN) data and Global Title Translation (GTT) data. GTT data is necessary for the routing of services such as Line Information Database service (LIDB), Custom Local Area Signaling Services (CLASS), Caller ID With Name (CNAM), and Interswitch Voice Messaging (ISVM). Upon reception of this information from the NPAC 11, the LSMS 12 populates the LRN and GTT functions deployed in the network elements 13-15 with the relevant data elements.
FIG. 2 is an illustrative drawing illustrating the steps involved when retrieving a Location Routing Number (LRN) in an existing telecommunications network having LNP service provisioning. At 21, a calling subscriber dials the telephone number of a called subscriber 26, for example 214-997-1234. The call is routed to an originating switch 22. There are triggers set up within the originating switch to recognize that the NPA-NXX (214-997) has been ported. Therefore, a lookup is performed in the LNP database 23 of a SCP associated with the originating switch to retrieve a LRN corresponding to the dialed telephone number. If the LNP database indicates that the dialed number is not ported, then the dialed number is returned to the originating switch. The originating switch then routes the call on the LRN at 24 to a destination switch 25 which handles the NXX in the retrieved number (e.g., 881). The dialed telephone number is saved in a GAP indicator. The destination switch replaces the LRN with the dialed telephone number since the called subscriber 26 is still using the dialed telephone number. The call completely bypasses the 997 NXX switch 27.
The existing LNP network configuration, the existing method of populating the network elements with LNP data, and the existing method of retrieving a LRN suffer from several disadvantages. First, the existing configuration is very expensive due to the implementation of mated pairs of SCPs or STPs for every network element node. The quantity of ported numbers is growing rapidly, and their storage requires ever increasing amount of memory. It would be advantageous to have a method of populating the nodes that did not require that the entire national LNP database be loaded into each node. A more cost-effective network configuration could then be implemented.
In addition, the existing method of populating the LSMSs with LNP data by the NPAC, and the subsequent population of the network element nodes is extremely inefficient. The ported numbers are transported one at a time. This limitation becomes even more pronounced when audits are performed between a LSMS and the network nodes which it populates. When thousands or millions of numbers are involved, the signaling load becomes very burdensome. It would be advantageous to have a more efficient method for the LSMS to populate the network elements.
There are no known prior art teachings of a solution to the aforementioned deficiency and shortcoming such as that disclosed herein.